Preventing emboli and other debris from entering the carotid arteries (i.e., the brachiocephalic artery, or right common carotid artery, and the left common carotid artery) by way of the aorta reduces the incidence of ischemic stroke. Emboli and other debris in the aorta may come from several sources. These sources include: 1) aortic atheroma which detaches from the wall of the aorta due to various reasons including incising, clamping, and/or clamp release of the aorta during surgery; 2) debris released during surgery on the heart such as the installation of a replacement heart valve; 3) thrombus which forms in the right atrium resulting from atrial fibrillation; 4) thrombus which forms on ventricular assist devices; 5) venous thrombus which passes into the left ventricle through a patent foramen ovale or other arteriovenous shunt; and 6) other less common sources.
A variety of intravascular filtering means are known in the art and may consist of a flexible metallic grid, a flexible synthetic or plastic grid, a weave of synthetic filaments, or a nondegradable or possibly biodegradable textile cloth, often supported by a basket or funnel shaped frame which may be deployed within the lumen of a vessel to be protected.
There are fewer intravascular devices designed for arterial and especially aortic filtration, much less diversion. An embolic debris diverter that functions in arteries must address additional concerns because of the hemodynamic differences between arteries and veins. Arteries are much more flexible and elastic than veins and, in the arteries, blood flow is pulsatile with large pressure variations between systolic and diastolic flow. These pressure variations cause the artery walls to expand and contract. Thus, filters and diverters must be able to expand and contract along with the lumen of the aorta to which they may be anchored. In addition, intravascular devices for aortic filtration and/or diversion of emboli typically occlude a significant portion of the lumen of the aorta rendering them unsatisfactory for use in combination with other intravascular interventional procedures.
Although the majority of debris is expected to be generated during a treatment or diagnostic procedure, it is known that the potential for ischemic stroke persists for a period of time after surgery. The problem of preventing emboli from reaching the cerebral vasculature following surgical intervention has thus far not been adequately addressed. Therefore, a need exists for new devices and methods to prevent embolic material from entering the carotid/cerebral arteries, while maintaining peripheral blood flow from the heart to the descending aorta. Such devices should be capable of remaining within the body for an extended period of time before being removed.